Paperboard cartons often are used to store articles that are easily broken, contaminated or otherwise subject to damage. Typically the carton will be constructed to properly retain and support the article therein. However, it also is necessary to insure that the carton is securely closeable to prevent the article from falling out. This is particularly important where the carton is likely to be moved while the article is stored therein.
In many instances the secure closure of the carton is insured by an adhesive, such as glue or tape, or by a separate plastic overwrap completely enveloping the carton. Although these types of secure closures typically are quite functional, they invariably require additional manufacturing steps, and can add to the cost of the carton. More particularly the equipment needed to securely close or overwrap often is not available to the manufacturer of the articles to be stored in the carton. Thus, the manufacturer of the articles to be stored in the carton may have to invest in expensive packaging equipment of limited application in the principal business of that manufacturer. Alternatively the product manufacturer may have to subcontract for the packaging of its manufactured products. This latter option often is undesirable since it may require an initial shipping of improperly packaged articles, and can reduce the direct control that the manufacturer has over its product. Additionally, in certain environments, the use of plastic tapes or overwraps is undesirable because plastic materials can create static electricity when moved relative to one another. Adhesives and overwraps are further undesirable in that they can fail or be tampered with thereby rendering the carton insecure. Furthermore, adhesives and overwraps may provide a secure initial closure of a carton, but can provide a much less secure reclosure.
For the reasons explained above, purely mechanical closures often are considered to offer several advantages. Specifically, mechanical closures can minimize the manufacturing steps and costs, and can provide for secure reclosures. Furthermore mechanical closure often can be completed without specialized equipment. However, prior art mechanical closures of cartons have often been less secure than closures relying upon adhesives and/or overwraps.
The typical prior art mechanical closure has relied upon an interengagement of locking tabs and slots. More particularly, a closure panel typically would be hingedly attached to a side wall of a carton and adapted to rotate into a position to cover an opening in the carton. A locking tab or flap would be hingedly attached to the closure panel of the prior art carton, and would be adapted to be inserted into a corresponding slot in an adjacent side wall of the carton. In certain constructions, the locking tab or flap would include at least one locking cut line dimensioned and located to be substantially in line with the slot in the carton side wall. These adjacent arrays of cut lines and/or slots would enable an edge of the locking flap defined by the locking cut line therein to abut an edge formed by the slot in the side wall. This edge-to-edge abutment is intended to minimize the possiblity of inadvertent disengagement of the locking flap from the side wall slot. Several variations of this general locking tab construction are well known, such as the particular construction shown in the bottom wall of the carton described in U.S. Pat. No. 3,163,321 which issued to Weiss on Dec. 29, 1964.
Despite several positive features of the above described prior art cartons, it is considered desirable to provide a carton with significantly enhanced locking ability.
In view of the above it is an object of the subject invention to provide a carton that can be securely locked into a closed condition without adhesives or overwraps.
It is another object of the subject invention to provide a paperboard carton that can be securely locked entirely by an interengaged array of locking flaps or tabs.
It is an additional object of the subject invention to provide a carton with a double insert locking flap or tab construction.
It is a further object of the subject invention to provide a carton with a redundant array of locking flaps or tabs for insuring secure positive closure thereof.
It is still another object of the subject invention to provide a securely locked carton that can be easily opened and readily reclosed.
It is still a further object of the subject invention to provide a carton that will show evidence of tampering.
Another object of the subject invention is to provide a carton that can be placed in a collapsed or knocked down condition and then easily erected for packing and secure mechanical locking without specialized equipment.